Changeable speed transmissions for bicycles have been proposed and used for many years. These have included various rear wheel hub transmissions, which typically achieved two or three specified speed reductions, as well as derailleur systems, which use a driving chain as a force transmitting element between selectable rear and/or front sprockets.
An improved transmission is described in U.S. Pat. No. 5,632,702 to Mills (the '702 patent), assigned to the assignee of the present invention and incorporated herein by reference. This patent discloses a continuously variable transmission. This patent further teaches the use of a sprocket which serves as an adjusting mechanism operably connected to an inner eccentric element and outer eccentric element. Adjusting the position of the inner eccentric element and the outer eccentric element adjusts the gearing of the transmission.
The '702 patent teaches the use of a worm gear to provide increased torque to the extension shaft of the disclosed adjustment mechanism. Such a configuration eases the adjustment and selection of the desired gear ratio provided by the transmission. This is favorable to reduce the impact of working forces exerted on the internal components of the transmission during operation.
U.S. patent application Ser. No. 08,991,815, now allowed, entitled Shift Mechanisms and Methods of Controlling a Transmission, filed Dec. 16, 1997, naming Ned Mills and Benjamin K. Jones as inventors, assigned to the assignee hereof, and incorporated herein by reference, discloses the use of a hydraulic shift mechanism for adjusting the gear ratio of a continuously variable transmission. Such utilizes a master cylinder and slave cylinder configuration to provide shifting of the transmission.
The present invention discloses apparatuses and methods of providing operator control of the gearing of a transmission.